The bottom line about Mr Plimsoll

In her compelling biography, The Plimsoll Sensation, Nicolette Jones details how Mariners, miners and beer drinkers alike all have good reason to thank a typically fertile Victorian inventor, says Simon Garfield

If we think of him at all, we think of gym shoes and lines around the sides of ships. When Nicolette Jones thinks of him, she sees a road in north London and a roughly painted pub sign, and a man who deserves fuller recognition as a saviour of souls. Eleven years ago, she moved to a Victorian terrace in Plimsoll Road, Highbury, and later bought a pub sign bearing his name for £20. She says she knew the name contained a story, but she misjudged precisely how complex the story would be. We would all have been similarly deceived: is there a simpler thing than putting a line on the side of a ship to define the lowest level at which it should lie in the water and thus prevent overloading? Is there a more irrepressible notion than one that attempts to save thousands of lives? In high-Victorian Britain, apparently so.

The line of beauty was first applied in 1876, when Plimsoll was 52. By that time, he had fought for it for six years and the bulk of Jones's biography is engaged with the tortuous journey of various merchant shipping bills through parliament. Like most pioneers, Plimsoll was ridiculed and championed in equal measure.

He was born in Bristol, moved to Sheffield, soon grew extreme facial hair, became friendly with Giuseppe Garibaldi and Richard Cobden and, by this account, enjoyed nothing more than extending his reputation as a bit of a stirrer. He liked to point out the iniquity of traffic and railway bylaws, but his big thing was social injustice and the callous pursuit of profit with disregard for human misery. He lived at a time when industrial progress was still largely unchecked by labour laws; speed and productivity dominated in the drive for the competitive edge in global trade and the expansion of Empire.

When he became MP for Derby at the second attempt in 1868, he embraced the entire Liberal catalogue: free trade, workplace and financial reform, an end to corruption and nepotism. He was no mousy backbencher, but was openly hostile to Disraeli and ended letters to his detractors with the instruction to 'do your worst'. His first speech, addressing the rights of the trade union movement, was typical fare, as was the reaction to it. Vested interests mocked that it was boring; in reality, they found it threatening.

Before he was known as 'the sailor's friend', he was 'the miner's friend', proposing cheap methods to detect gas underground and fundraising energetically after pit disasters. Before that, he was everyone's friend, inventing little gadgets that improved the quality of life, three of which represented Sheffield at the Great Exhibition of 1851: an insulating enamel, a new, adaptable file handle and a pocket umbrella. He also found a new way of straining impurities from beer.

Unlike many other Victorians with comparable reformist zeal, Plimsoll, a low-church Anglican and one-time brewery manager, was not a teetotaller. Jones attempts to show that he was even quite fun, although you probably had to be there.

His big mission was inspired by several major accidents at sea and the fear he perceived from most sailors before a voyage. Cargo ships setting sail in the 1860s were very likely to be unseaworthy, both badly maintained and overloaded. If these 'coffin ships' sank, their over-insured owners usually cashed in at Lloyd's. Plimsoll rallied for regular enforced inspections and, in 1870, encouraged by his first wife, Eliza, seized upon an idea proposed by shipowner James Hall. The idea soon became his ticket to posterity: a level of maximum submergence.

Plimsoll's own level of near-fatal submergence is expertly tracked by Jones, who notes how his obsessions almost ruined him financially and certainly damaged his health. By the time of his death in 1898, some of his fame had dissipated. There are various statues and plaques in his memory, but not much is heard these days of the many music hall songs composed in his honour. Just as well; they're printed in full in an appendix and I'm not sure even a stirring clash of cymbals and brass would make them bearable.

· To order The Plimsoll Sensation for £18 with free UK p&p, go to observer.co.uk/bookshop or call 0870 836 0885